The mirror neuron system and action recognition
Introduction
Action recognition is a fundamental step on which social behavior depends. Although numerous hypotheses have been forwarded to explain action recognition (see Barresi & Moore, 1996), two main theories may explain this cognitive function (Rizzolatti, Fogassi, & Gallese, 2001). The first one, often referred as the “visual hypothesis”, maintains that action recognition relies on a visual analysis of all constituents of a specific action, that is a visual analysis of the effector involved, of the object on which the action is acted upon, and finally, of the context in which the action is going on. Inference about the interactions between all these elements visually described would allow the observer to understand and recognize actions performed by others. If this hypothesis were true, the neural substrates involved in action recognition would be the visual extrastriate areas, the inferotemporal lobe and the superior temporal sulcus region. The second one, referred as the “direct-matching hypothesis”, maintains that one can recognize actions performed by others by mapping the observed action on his/her own motor representation of the observed action. According to this hypothesis, action observation automatically activates in the observer the same neural structures involved in the actual execution of the observed action. Since the result of the activation of these neural substrates during action execution is known, the activation of the same substrates during action observation would allow the observer, through an observation–execution matching mechanism, to understand what the actor is doing. This latter hypothesis has recently found a strong neurophysiological support in the discovery of the mirror neuron system. This review will focus on the organization of the mirror neuron system both in the monkey and humans, and on the experimental evidence of its involvement in action observation and recognition.
Section snippets
Mirror neuron system in the monkey
The rostral part of monkey ventral premotor cortex is called area F5, according to the nomenclature proposed by Matelli, Luppino, and Rizzolatti (1985). Electrophysiological studies have shown that in this area there is a motor representation of mouth and hand actions. Neurons related to hand actions discharge when the monkey executes specific goal-directed hand actions such as grasping, holding, tearing and manipulating objects. It has been proposed that these neurons constitute a sort of
Mirror neuron system in humans
There is increasing evidence that a mirror neuron system also exists in humans. Converging data supporting this notion come from experiments carried out with neurophysiological, behavioral and brain imaging techniques.
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